Belspo-Bilateral agreements (1997-2000)

Glacier fluctuations and climatic change in South Siberia

Project description

Global mean temperatures have risen over the
past 100 years by about 0.6°C. Over half of the increase
has occurred in the last 25 years (IPCC). Glaciers all over the
world react to these variations in background temperature, primarily
by retreating. This is valid for most glaciers outside Antarctica
or Greenland. They are therefore considered to be potentially
good climatic indicators.

One way to determine the state of a glacier
is by determining its mass balance. During winter, a glacier
gains mass from accumulating snow. During the following summer
some, and sometimes all, of that winter accumulation is lost
due to melt. The difference between the accumulation and melt
(or ablation) describes the annual net mass balance, which
is equal to change in glacier volume.Mass balance measurements
on more than 280 glaciers all over the world indicate that in
most regions of the world, glaciers are shrinking in mass.

The
majority of source information with respect to the dynamic
response of temperate glaciers with changing climate comes from
European and, to a lesser extent, North-American glaciers, while
the share of the European glaciers in the world glacier area
consists of only 3%. Hence, our knowledge on the glaciers of
remote and hardly accessible mountain regions, often characterized
by a high degree of glacierization, is rather limited. This biased
distribution of glaciological source information severely constrains
present attempts to assess the impact of climate change on the
global glacier volume. It also hampers a full understanding of
glacier dynamics and the impact of different climatic conditions.
This project intends to expand the current global glaciological
record by presenting and analyzing data gathered on Sofiyskiy
Glacier, located in the Russian Altai Mountains, and collected
during four consecutive summer field seasons in the period 1997-2000.

The
climate of the Altai Mountains exhibits two important characteristics
which contribute to the specific interest of this study area.
First, the extreme continentality gives rise to aridity and
large diurnal and seasonal temperature range. Second, owing to
the coincidence of both accumulation and ablation season in summer,
we can characterize the Altai glaciers as summer-accumulation
type glaciers. Although current knowledge on the behaviour
of these glaciers is limited, they are reported to be more vulnerable
to the current global warming trend than the better known (maritime)
winter-accumulation type glaciers. During this project, the
basic characteristics of Sofiyskiy Glacier were investigated,
such as surface mass balance and velocity, and the historical
front variations. To gain a better understanding of the glacier's
dynamics, we also performed a force-balance analysis and an analysis
of basal conditions using a three-layer reflectivity model for
electromagnetic pulses.